This invention relates generally to the field of fasteners for printed circuit board applications and, in particular, to a means and method for harnessing or retaining optical fiber to a printed circuit (PC) board or the like.
It is conventional to process or route information to and from many types of electronic devices via fiber optic cables, especially when large amounts of data or large numbers of signals need to be transmitted. Typically, the electronic devices include printed circuit boards with various components used to process the signals or perform needed operations. The components may include typical electronic and opto-electronic devices such as transceivers and so on. Typically, one end of a fiber optic cable is fastened to the circuit board by a connector that allows communication with an incoming or external fiber optic cable. A length of fiber optic cable may then extend from the connector to a device attached to the circuit board and thus permit data transmission therebetween.
However, fiber optic cable has physical limitations, notably the bending it can withstand without failure. The limitation on the bending that a fiber optic cable can withstand prior to failure is known as the minimum bend radius. Due to this physical limitation, devices have been created to manage or harness fiber optic cable to a printed circuit board in such a manner as to prevent over bending of the fiber optic cable and to prevent entanglement of the cable with adjacent components or boards, especially during installation of the board. One such harnessing or retaining device is a retaining eye loop. This prior art device resembles a ring mounted upon a post. The post includes an arrow-shaped connector or head portion opposite the ring, which, when inserted through an opening in a circuit board, expands on the far side of the board and holds the retaining device in place. Examples of such snap leg latches are shown in FIGS. 1 and 2 of U.S. Des. Pat. No. 278,143 (see also, U.S. Pat. Nos. 5,281,149, 5,255,159, and 6,058,579).
However, a disadvantage of such a retaining device is the difficulty of insertion of the connector portion, which can damage or break the circuit board. Further, the extent to which the retaining device extends outwardly from the circuit board, front and back, when installed, can increase the effective thickness of the circuit board, interfere with installation and damage adjacent components.
Accordingly, it would be desirable to provide an apparatus and method of providing improved retension of fiber optic cable to a circuit board, or the like, which overcomes the disadvantages described above.
One aspect of the present invention provides a spool retainer apparatus for providing retention of fiber optic cable to a circuit board. The spool retainer for retaining a length of fiber optic cable to a circuit board includes a spool-shaped body portion. The body portion of the apparatus includes a plurality of spaced legs extending from the body portion, each of the legs is adapted to be received in a mounting opening formed in the PC board. Each of the spaced legs can include a foot portion adapted for securing the body to the circuit board. The spool retainer body includes a cylindrical portion. Each one of a pair of annular flanges is positioned at one end of the cylindrical portion. The spool body portion defines a channel for retaining the fiber optic cable in an arc having a radius greater than a minimum bend radius of the fiber optic cable.
Another aspect of the present invention provides a retaining spool for a PC board for retaining a length of fiber optic cable including a body portion. The body portion includes a channel defined about the periphery thereof for receiving the fiber optic cable in an arc having a radius greater than a minimum bend radius of the fiber optic cable and a plurality of legs extending from the body portion. Each of the legs is adapted to be received in an opening formed in the PC board.
In other aspects of the present invention, the body portion may include a center portion and upper and lower flange portions. The center portion may have the form of a cylinder. The upper and lower flange portions can define the channel with the center portion. The body portion may include a plurality of posts formed on the center portion. The posts may extend in a generally axial direction and may be inserted into corresponding openings formed in the upper and lower flange portions for positioning the flange portions on the center portion. At least one of the lower and upper flange portions may include at least one tab positioned to close the channel for retaining the fiber optic cable therein.
Each of the legs may include a foot portion positioned at the distal end of each the leg being adapted for securing the retaining spool to the PC board. Each of the legs may include a cross piece positioned between the foot portion and the body portion. The legs may extend from the body angled outwardly with respect to the axial direction. The legs may be attached to the lower flange portion at an outer edge thereof. The legs can be attached to the central portion from an inner wall thereof. Each foot may extend at an angle from each leg. Each foot may be formed at an orientation substantially parallel to the plane of the PC board when the retaining spool is affixed thereto. The retaining spool may include four legs. The retaining spool may preferably be made of a resilient material. The resilient material may be metal or plastic.
Another aspect of the present invention provides a PC board and retaining spool assembly for retaining a length of fiber optic cable thereto including a PC board including a plurality of mounting openings and a retaining spool. The retaining spool includes a body portion defining a channel formed thereabout and a plurality of spaced legs attached to the body portion. The legs are positioned for insertion into the mounting openings to secure the retaining spool to the PC board. A length of optic cable is retained in the channel of the retaining spool.
Another aspect of the present invention provides a method of operation of a retention spool that is adapted to be mounted directly to a PC board for retaining a length of fiber optic cable thereto including providing a channel about the periphery of the retention spool, the channel having a radius greater than a minimum bend radius of the fiber optic cable. A plurality of openings is provided through the PC board in a spaced apart configuration. Pressure is applied to a plurality of legs on the retention spool. Each leg is inserted into a corresponding one of the plurality of openings on the PC board. Pressure is released from the plurality of legs to retain the retention spool to the PC board. The length of fiber optic cable is inserted into the channel in the retention spool and the length of fiber optic cable is thus retained to the retention spool.
The invention provides the foregoing and other features, and the advantages of the invention will become further apparent from the following detailed description of the presently preferred embodiments, read in conjunction with the accompanying drawings. The detailed description and drawings are merely illustrative of the invention and do not limit the scope of the invention, which is defined by the appended claims and equivalents thereof.